#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>

#include <Wire.h>               // Only needed for Arduino 1.6.5 and earlier
#include "SSD1306Wire.h"
SSD1306Wire display(0x3c, 2, 14); 


const char* ssid = "vincent";
const char* password = "012345678";

const char* username = "31901040";
const char* user_password = "012345678";
ESP8266WebServer server(80);

//Check if header is present and correct
bool is_authenticated() {
  Serial.println("Enter is_authenticated");
  if (server.hasHeader("Cookie")) {
    Serial.print("Found cookie: ");
    String cookie = server.header("Cookie");
    Serial.println(cookie);
    if (cookie.indexOf("ESPSESSIONID=1") != -1) {
      Serial.println("Authentication Successful");
      return true;
    }
  }
  Serial.println("Authentication Failed");
  return false;
}

//login page, also called for disconnect
void handleLogin() {
  String msg;
  if (server.hasHeader("Cookie")) {
    Serial.print("Found cookie: ");
    String cookie = server.header("Cookie");
    Serial.println(cookie);
  }
  if (server.hasArg("DISCONNECT")) {
    Serial.println("Disconnection");
    server.sendHeader("Location", "/login");
    server.sendHeader("Cache-Control", "no-cache");
    server.sendHeader("Set-Cookie", "ESPSESSIONID=0");
    server.send(301);
    return;
  }
  if (server.hasArg("USERNAME") && server.hasArg("PASSWORD")) {
    if (server.arg("USERNAME") == username &&  server.arg("PASSWORD") == user_password) {
      server.sendHeader("Location", "/");
      server.sendHeader("Cache-Control", "no-cache");
      server.sendHeader("Set-Cookie", "ESPSESSIONID=1");
      server.send(301);
      Serial.println("Log in Successful");
      return;
    }
    msg = "Wrong username/password! try again.";
    Serial.println("Log in Failed");
  }

  // 获取客户端IP地址
  WiFiClient get_client = server.client();
  Serial.println(get_client.remoteIP());

  display.clear();
  display.drawString(10, 10, "Client  IP: ");
  display.drawString(10, 26, get_client.remoteIP().toString());
  display.display();
  
  String content = "<html><body><h1>31901040</h1><form action='/login' method='POST'>To log in, please use : admin/admin<br>";
  content += "User:<input type='text' name='USERNAME' placeholder='user name'><br>";
  content += "Password:<input type='password' name='PASSWORD' placeholder='password'><br>";
  content += "<input type='submit' name='SUBMIT' value='Submit'></form></body></html>" + msg + "<br>";
//  content += "You also can go <a href='/inline'>here</a>";
  server.send(200, "text/html", content);
}
void handleGpio1(){
  Serial.println("Enter handleGpio1");
  String header;
  if (!is_authenticated()) {
    server.sendHeader("Location", "/login");
    server.sendHeader("Cache-Control", "no-cache");
    server.send(301);
    return;
  }
  String content = "<html><body><H2>31901040</H2><br>";
  content += "IO0:" + String(digitalRead(0)) + "<br>";
  content += "</body></html>";
  server.send(200, "text/html", content);
}
//root page can be accessed only if authentication is ok
void handleRoot() {
  Serial.println("Enter handleRoot");
  String header;
  if (!is_authenticated()) {
    server.sendHeader("Location", "/login");
    server.sendHeader("Cache-Control", "no-cache");
    server.send(301);
    return;
  }
  String content = "<html><body><H1>successfully connected to esp8266!</H1><h2>31901040</h2>";
  content += "IO0:" + String(digitalRead(0)) + "<br>";
  content += "IO1:" + String(digitalRead(1)) + "<br>";
  content += "You can access this page until you <a href=\"/login?DISCONNECT=YES\">disconnect</a></body></html>";
  server.send(200, "text/html", content);
}

//no need authentication
void handleNotFound() {
  String message = "File Not Found\n\n";
  message += "URI: ";
  message += server.uri();
  message += "\nMethod: ";
  message += (server.method() == HTTP_GET) ? "GET" : "POST";
  message += "\nArguments: ";
  message += server.args();
  message += "\n";
  for (uint8_t i = 0; i < server.args(); i++) {
    message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
  }
  server.send(404, "text/plain", message);
}

void setup(void) {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());


  server.on("/", handleRoot);
  server.on("/login", handleLogin);
  server.on("/gpio/1", handleGpio1);

  server.onNotFound(handleNotFound);
  //here the list of headers to be recorded
  const char * headerkeys[] = {"User-Agent", "Cookie"} ;
  size_t headerkeyssize = sizeof(headerkeys) / sizeof(char*);
  //ask server to track these headers
  server.collectHeaders(headerkeys, headerkeyssize);
  server.begin();
  Serial.println("HTTP server started");
  display.init();
  display.flipScreenVertically();
  display.setFont(ArialMT_Plain_16);
}

void loop(void) {
  server.handleClient();
}
